Solution
= Solution
For the pure state $\sigma_{RQE}$ induced by a purification and <Stinespring dilation>, the <coherent information> is
$$
\boxed{I_c(\Lambda,\rho)=S(\sigma_Q)-S(\sigma_E)
=-H(R|Q)_\sigma}.
$$
= Solution
For the pure state $\sigma_{RQE}$ induced by a purification and <Stinespring dilation>, the <coherent information> is
$$
\boxed{I_c(\Lambda,\rho)=S(\sigma_Q)-S(\sigma_E)
=-H(R|Q)_\sigma}.
$$